BSA206 Database Management Systems Lecture 2: Introduction to Oracle / Overview of Database Concepts

Lecture 2 / Slide 2 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Chapter Objectives  Identify the purpose of a database management system (DBMS)  Distinguish a field from a record and a column from a row  Identify the basic components of an Entity-Relationship Model  Define the three types of relationships that can exist between entities

Lecture 2 / Slide 3 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Chapter Objectives  Identify the problem associated with many-to-many relationships and the appropriate solutions  Explain the purpose of normalization  Describe the role of a primary key  Identify partial dependency and transitive dependency in the normalization process

Lecture 2 / Slide 4 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Chapter Objectives  Explain the purpose of a foreign key  Determine how to link data in different tables through the use of a common field  Explain the purpose of a structured query language (SQL)

Lecture 2 / Slide 5 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Database Terminology  Database – logical structure to store data  Database Management System (DBMS) – software used to create and interact with the database

Lecture 2 / Slide 6 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Database Components  Character  Field  Record  File

Lecture 2 / Slide 7 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Database Components - Character  Basic unit of data  Can be a letter, number, or special symbol

Lecture 2 / Slide 8 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Database Components - Field  A group of related characters  Represents an attribute or characteristic of an entity  Corresponds to a column in the physical database

Lecture 2 / Slide 9 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Database Components - Record  A collection of fields for one specific entity  Corresponds to a row in the physical database

Lecture 2 / Slide 10 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Database Components - File  A group of records about the same type of entity

Lecture 2 / Slide 11 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Components Example

Lecture 2 / Slide 12 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Review of Database Design  Systems Development Life Cycle (SDLC)  Entity-Relationship Model (E-R Model)  Normalization

Lecture 2 / Slide 13 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Systems Development Life Cycle (SDLC)  Systems investigation – understanding the problem  Systems analysis – understanding the solution  Systems design – creating the logical and physical components

Lecture 2 / Slide 14 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Systems Development Life Cycle (SDLC)  Systems implementation – placing completed system into operation  Systems maintenance and review – evaluating the implemented system

Lecture 2 / Slide 15 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Entity-Relationship Model (E-R Model)  Used to depict the relationship that exists among entities

Lecture 2 / Slide 16 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 E-R Model Symbols

Lecture 2 / Slide 17 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Relationships  The following relationships can be included in an E-R Model: –One-to-one –One-to-many –Many-to-many

Lecture 2 / Slide 18 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 One-to-one Relationship  Each occurrence of data in one entity is represented by only one occurrence of data in the other entity  Example: Each individual has just one Social Security Number (SSN) and each SSN is assigned to just one person

Lecture 2 / Slide 19 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 One-to-many Relationship  Each occurrence of data in one entity can be represented by many occurrences of the data in the other entity  Example: A class has only one instructor, but each instructor can teach many classes

Lecture 2 / Slide 20 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Many-to-many Relationship  Data can have multiple occurrences in both entities  Example: A student can take many classes and each class is composed of many students  Can not be included in the physical database

Lecture 2 / Slide 21 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Example E-R Model

Lecture 2 / Slide 22 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Normalization  Determines required tables and columns for each table  Multi-step process  Used to reduce or control data redundancy

Lecture 2 / Slide 23 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Unnormalized Data Contains repeating groups in the Author column in the BOOKS table

Lecture 2 / Slide 24 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 First-Normal Form (1NF)  Primary key is identified  Repeating groups are eliminated

Lecture 2 / Slide 25 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 First-Normal Form (1NF) ISBN and Author columns together create a composite primary key

Lecture 2 / Slide 26 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Composite Primary Key  More than one column is required to uniquely identify a row  Can lead to partial dependency - a column is only dependent on a portion of the primary key

Lecture 2 / Slide 27 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Second-Normal Form (2NF)  Partial dependency must be eliminated –Break the composite primary key into two parts, each part representing a separate table

Lecture 2 / Slide 28 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Second-Normal Form (2NF) BOOKS table in 2NF

Lecture 2 / Slide 29 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Third-Normal Form (3NF) Publisher contact name has been removed

Lecture 2 / Slide 30 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Summary of Normalization Steps  1NF: eliminate repeating groups, identify primary key  2NF: table is in 1NF and partial dependencies eliminated  3NF: table is in 2NF and transitive dependencies eliminated

Lecture 2 / Slide 31 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Linking Tables  Once tables are normalized, make certain tables are linked  Tables are linked through a common field  A common field is usually a primary key in one table and a foreign key in the other table

Lecture 2 / Slide 32 Introduction to Oracle9i: SQL, Morris-Murphy ©2003

Lecture 2 / Slide 33 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 JustLee Books’ Database Assumptions –No back orders or partial shipments –Only USA addresses –Shipped orders are purged (deleted) at the end of the month

Lecture 2 / Slide 34 Introduction to Oracle9i: SQL, Morris-Murphy ©2003 Structured Query Language (SQL)  Data sublanguage  Used to: –Create or modify tables –Add data to tables –Edit data in tables –Retrieve data from tables